International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 06 Issue: 05 | May 2019
p-ISSN: 2395-0072
www.irjet.net
Pushover Analysis of Vertically Regular and Irregular Steel Structure Ajinkya Hasabe1, R.D.Patil2 1M.
Tech. student, Dept. of Civil-structural Engineering, RIT, Maharashtra, India Dept. of Civil-structural Engineering¸ RIT, Maharashtra, India ---------------------------------------------------------------------***---------------------------------------------------------------------2Professor,
Abstract - In last decades Steel structure has played an important role in construction Industry. It is necessary to design a structure to perform well under seismic loads. During an earthquake, failure of structure starts at points of weakness. This weakness arises due to discontinuity in mass, stiffness and geometry of structure. Vertical irregularities are one of the major reasons of failures of structures during earthquakes. In this paper we are going to perform push over analysis of regular steel building and buildings having irregularities such as mass and stiffness using ETAB 2016 software.
1.2 Types of Vertical Irregularities
Key Words: Vertical irregularity, pushover analysis, storey drift
3) Geometric Irregularity- Vertical geometric irregularity shall be considered to exist, when the horizontal dimension of lateral force resisting system in any storey is more than 125 percent of the storey below.
1) Mass IrregularityMass irregularity shall be considered to exist, when the seismic weight of any floor is more than 150 percent of that of the floor below. 2) Stiffness Irregulariy (Soft Storey)Soft storey is a storey whose lateral stiffness is less than that of storey above.
1. INTRODUCTION Now days, as in the urban areas the space available for the construction of buildings is limited. So in limited space we have to construct such type of buildings which can be used for multiple purposes such as lobbies, car parking etc. To fulfill this demand, buildings with irregularities is the only option available. A performance based seismic analysis can be used for various purposes such as assessment of large structures, design verification of new construction, evaluation of an existing structure to identify damage states for various amplitudes of ground motions. So, the effect of vertically irregularities in the seismic performance of structures becomes really important. In this paper three models are considered of which one is regular and other two having mass and stiffness irregularity. Pushover analysis of these models is carried out using ETABS 2016 software and results are compared.
2.1 Modeling and Analysis To study the seismic response of Steel structure, G+8 multistoried buildings with mass irregularity, stiffness irregularity and one regular building are considered. The modeling and analysis of work is done by using ETABS software. The basic material properties used are as follows: • Modulus of Elasticity of steel, Es = 20,0000 MPa • Modulus of Elasticity of concrete, Ec = 27386.12 MPa • Grade of concrete = M20 Details of models:
1.1 Vertical Irregularity
Table -1: Parameters considered for modeling
Vertical irregularity results from the uneven distribution of mass, strength, stiffness along the elevation of a building structure. Mass irregularity results from a sudden change in mass between adjacent floors, such as mechanical plant on the roof of a structure. Stiffness irregularity results from a sudden change in stiffness between adjacent floors, such as setbacks in the elevation of a building. IS 1893 (Part1): 2016 gives details about vertical irregularities in structure.
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Impact Factor value: 7.211
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Type of Building
Steel
No. of story
G+8
Height of floor
3m
Type of building
Residential
Seismic zone
4
Importance factor
1.2
Response reduction factor
5
Type of soil
Medium soil
Grade of steel
Fe345
ISO 9001:2008 Certified Journal
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